Power transistors may be used as switches in power electronic systems. The switches alternate between conducting a high current in the on-state and blocking a high voltage in the off-state. Two important figures of merit for power switches are low power losses during forward conduction and low power losses during switching between on and off. Low power losses are beneficial because they enable energy savings and because more compact systems can be constructed as the heat dissipation caused by the power losses is reduced.
Silicon carbide (SiC) bipolar junction transistors (BJTs) are power transistors that have the advantage of providing substantially lower power losses during conduction and switching as compared to standard silicon (Si) power transistors thanks to the high breakdown electric field of SiC. In addition, SiC has a high thermal conductivity and is a wide bandgap semiconductor and may therefore advantageously be used for manufacturing devices for high power, high temperature and high frequency applications.
Thus, there is a need for providing new designs of SiC BJTs and new methods of manufacturing such BJTs that would alleviate at least some of the above-mentioned drawbacks.